I'm with them too, and for the same reason because they were lowest with non black box.
They've been perfectly fine the two times I did interact with them. The first time they charged us money as I didn't declare a claim that was made against my mother that didn't actually happen, but this was quickly resolved via email with no problem. I called them up once to change address and the lady was very friendly and helpful.
So yeah no problems though I've never experienced what happens if you claim from them etc